With full crypto signing, then I prob will. But there will be limit as to what is allowed from external sources.
I am thinking along the lines that most IoT devices in the network will not have the compute power to be nodes, so there will be a "gateway" that is a node and it will vet any messages and the only messages it will look at are ones from sources it expects. Then the message has to be correctly formed and signed.
Messaging will be huge for IoT, and with Safe network messaging will solve a lot of the security issues that are in IoT devices exposed to the web. It becomes possible to filter what the device listens to.
Of course if people program their device to listen to anyone then security is just like the current web.